1. Field of the Invention
The present invention relates to suppressing an oversteer (OS) or an understeer (US) in the turn running of the vehicle.
2. Description of the Prior Art
It is known in the art of vehicles that when the vehicle is in an oversteered condition, such a condition is suppressed by the distribution of the driving force between the front and rear wheels being shifted forward so that the driving force of the front wheels is increased relative to that of the rear wheels, while when the vehicle is in an understeered condition, such a condition is suppressed by the distribution of the driving force between the front and rear wheels being shifted rearward so that the driving force of the rear wheels is increased relative to that of the front wheels, provided that the distribution of the driving force between the front and rear wheels is variable.
It is also known in this art that when the vehicle is in an oversteered or an understeered condition, such a condition is suppressed by the steering angle by the driver being modified by an electronic control unit (CPU) incorporating a microcomputer in being transmitted to the steered wheels.
Further, it is also known in this art that, when the respective wheels of the vehicle can each be selectively braked under the control of an electronic control unit, an oversteered condition is suppressed by the front wheel serving at the outside of the turn being braked, while an understeered condition is suppressed by the rear wheels, particularly the rear wheel serving at the inside of the turn being braked.
In Japanese Patent Laid-open Publication 2003-159966, it is described that, in order to control the running movement of the vehicle to be always most appropriate in spite of changes of the running conditions of the vehicle, particularly changes of the performance of the behavior control device in controlling the running movement of said vehicle by a plurality of behavior control devices, the target longitudinal force, the target lateral force and the target yaw moment are calculated, control responsive frequency characteristic values of the steering control device and the driving/braking force control device are calculated with respect to each wheel, weighting factors proportional to a reciprocal of each frequency characteristic value is calculated, the target slip ratios and the target slip angles of the respective wheels are calculated by a distribution control using a judging function based upon the weighting factors, and the steering angles and the braking pressures of the respective wheels and the engine output torque are controlled to accomplish the target slip ratios and the target slip angles.